US2591926A - Inert gas shielded arc welding method - Google Patents

Description

April 8, 1952 G. J. GIBSON ET AL 2,591,925

INERT GAS SHIELDED ARC WELDING METHOD Filed July's, 1948 lNvr-:NToRS GILBERT RROTHSCHILD BY GLENN J. GIBSON @m --Z r @im ATTORNEYS Patented Apr. 8, 1952 INERT GAS SHIELDED ARC WELDING METH Glenn J. Gibson, Chatham, and Gubert R. Rothschild, Somerville, N. J., assignors to Air Reduc tion Company, Incorporated, a corporation of New York Application July 3, 1948, Serial No. 37,037

(Cl. 21S- 10) 6 Claims.

This invention relates to inert gas shielded are :welding electrode, and the inert gas is usually projected ,against the work from the electrode holder in the form of a stream that surrounds the tip of the electrode, the arc, and the Weld puddle.

The gases vthat have been used With the most success for the gas shield are helium and argon. Since each of these gases is completely inert, it'might be assumed that the same results would be obtained when using one of them for the gas Vshield as when using the other, but it has been found that this is not the case. When using helium as the shielding gas, greater Weld penetration and hence greater Welding speed can be obtained for any given Welding current. However, heliuxn has a tendency to make the arc unstable. 'Moreoven helium is not altogether suitable for use by 'itself for the shielding gas When welding aluminum because of its tendency to darken the Weld or cause it to turn out dull and gray and have a porous character.

Argon has a pronounced cleansing action at the surface of the Weld puddle and is therefore better adapted for use as the shielding gas when welding aluminum because it causes the iinished Weld to turn out bright, shiny, and non-porous. For most metals it has a decided stabilizing iniluence on the arc. The principal objection to its use is the small Weld penetration obtained for any given Welding current as compared with that obtained With helium.

For the above reasons, it has heretofore been the practice to use argon as the shielding gas When welding aluminum and to use either argon or helium when welding other metals.

We have discovered that when Welding aluminum, if a mixture of helium and argon is used for the shielding gas in the proper proportions, results can be obtained that are not obtainable when either gas is used alone. We have also found this to be true in the welding of certain other metals such as stainless steel and similar alloy steels.

The principal object of the invention, therefore, is to provide an improved way of arc welding aluminum by the inert gas shielded method, and a further object is to provide an improved Way of Welding other metals such as stainless steel and the like by this method.

According to the invention, when Welding aluminum, a shielding gas mixture is employed containing enough argon to produce a cleansing action on the Weld puddle and to produce a bright, shiny, and non-porous Weld. As much helium as possible is included in the mixture to increase Weld penetration and the Welding speed Without sacricing to too great an extent the beneficial results obtained by the use of the argon. We have found that if the mixture contains argon and 20% helium by volume, a very satis- 'factory aluminum Weld is obtained which is nonporous and has a good shiny appearance, and sufficient penetration will be obtained for some operations. Also, this amount of argon will result in good arc stability. The more helium there is in the mixture, the better will be the penetration, and we have ascertained that the content of helium can be increased up to 6,0% for this purpose without materially sacrificing the good quality of the weld and its appearance, but beyond this amount of helium the Weld becomes porous and turns out dull and gray and the arc becomes unstable. The permissible range of the helium content is therefore from 20% to 60% by volume, the balance in any case being argon. The best compromise in the desirable results has been obtained when the helium constitutes anywhere from 40% to 50% of the mixture, and therefore this is the preferred range for the helium content.

When welding stainless steel and similar alloy steels helium has heretofore usually been used for the shielding gas, but We have found that it is desirable to use along with the helium an amount of argon which Will improve arc stability without causing too much loss in Weld penetration and Welding Speed. It has been ascertained that i1 a mixture of helium and argon is used for the shielding gas the helium content can be reduced to 60% and used with 40% of argon to obtain good arc stability, vor evenlreduced as low as 20% and used With 80% of argon to obtain even better arc stability, Without the reduction in weld penetration becoming a serious factor. While the tendency of the helium to produce a weld that is dull and lacks a bright shiny appearance is not so objectionable when welding stainless steel and similar alloy steels as when Welding aluminum, nevertheless, the argon that is used in the mixture primarily for the purpose of obtaining better arc stability .does result in a weld having a brighter appearance than when an al1- helium shielding gas is employed and assures a non-porous weld. The permissible range of the helium. content of the shielding gas mixture when welding stainless steel and similar allot7 steels in accordance with the invention is therefore the same as when welding aluminum, namely, from 20% to 60% by volume, the balance in any case being argon.

Actual use of a shielding gas containing helium and argon in the above stated proportions has shown that aluminum welding operations can be speeded up considerably due to vthe presence of helium in the mixture and yet the bright, shiny, and non-porous character of the Weld isretained, and also a more stable arc. is obtained, especially with A.C. welding. Also, when welding stainless steel and similar alloy steels, it has been found that a satisfactory welding speed can be maintained, While the presence of the argon renders the arc more stable, especially when welding with alternating current, and tends to give the weld a good appearance and eliminate porosity. These are results which are not obtainable by using for the shielding gas either helium or argonalone.

Any suitable apparatus maybe employed for arc welding metals in accordance with the invention. The single figure of the accompanying drawing diagrammatically illustrates one type of apparatus which may be used.

Referring to the drawing, I represents an electrode holder supporting an electrode II. The electrode is preferably a non-consuming electrode made of tungsten. The electrode and the workpiece .W are electrically connected to a source of welding current, such as a generator or transformer, by means of the conductors I2 and I3.

,ThusW-henwelding current is supplied, an arc 'I may be maintained between the tip of the electrode and the work-piece to effect the desired welding operation. The electrode holder has a gas chamber .I5 from which the. shielding gas is adapted to be projected against the work-piece in the form of a stream surrounding the. tip of the electrode, the arc Ill, and the weld puddle.

A cylinder' or other container I6 containing compressed helium, is provided with a valve Il .and a pressure regulator I8 so that the helium may be released at the desired pressure. Pressure gauges I9 and 20 indicate the pressure of the helium within the cylinder and its pressure after it passes. through the pressure regulator I8. The helium is delivered through a pipe 2|, controlled by a valve 22, to a iiowmeter 23, and thence to the pipe 24, controlled by a valve 25, which delivers .the helium to the gas chamber I5.

Another cylinder or container 26 contains compressed argon. A valve 21 controls the discharge of argon from the cylinder. The argon passes through a pressure regulator 28, and pressure gauges 29 and 3D indicate the pressure of the argon within the cylinder and its pressure after it passes through the pressure regulator. The argon is delivered through a pipe 3|, controlled Aby a valve 32, to a iiowmeter 33, and thence to the above-mentioned pipe 24 which leads to the gas chamber l 5.

By the means above described, a mixture of helium and argon in the proportions above specified can be delivered to the gas chamber I5 to provide the gas shield.

We claim.:

1. In an arc Welding method the improvement which comprises blanketing the arc with a homogeneous mixture of helium and argon in which from 20% to 60% of the mixture by volume is helium and the balance is argon.

2. Inan arc welding method the improvement which comprises blanketing the arc with a homogeneousmixture of helium and argon in which from 40% to 50% of the mixture by volume is helium and the balance is argon.

3. In the method of arc welding aluminum the improvement which comprises delivering to the region of the arc to iorm a protective gaseous shield, a homogeneous mixture of helium and argon in which from 20% to 60% of the mixture by volume is helium and the balance is argon.

4. In the method of arc welding aluminum the improvement which comprises delivering to the region of the arc to form a protective gaseous shield, a homogeneous mixture of helium and argon in which from 40 to 50% of the mixture by volume is helium and the balance'is argon.

5. An arc welding method which comprises striking an arc between a non-consuming electrode. and a metallic work-piece, and delivering to the region of the arc to form a protective. gase. ous shield for the tip of the electrode, the arc, and the weld puddle, a homogeneous mixture of heliumand argon in which from 20% to 60% of the mixture by volume is helium and the balance is argon.

6. The method of welding aluminum which comprises striking an arc between a non-consuming electrode and the aluminum work-piece, and

delivering to the region of the arc to form aprotective gaseous shield for the tip of the electrode, the arc, and the weld puddle, a homogeneous mixture of helium and argon in which from 20% to 60% of the mixture by volume is helium and the balance is argon.

GLENN J. GIBSON.

GILBERT R. ROTHSCHILD.

REFERENCES CETED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name DateA 2,053,417 Brace Sept. 8, 1936 2,522,482 Olzak Sept. 12, 1950 OTHER REFERENCES General Electric Review, July 1944, pages 2l-26, particularly pages 21 and 22.

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